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SubjectRe: [PATCH] x86: kprobes change kprobe_handler flow
Abhishek Sagar wrote:
> Masami Hiramatsu wrote:
...
> Done. You should find the desired changed in this patch.

Well done!
This cleans it up very well.
I have just one more comment.

> @@ -463,14 +487,26 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
> arch_disarm_kprobe(p);
> regs->ip = (unsigned long)p->addr;
> reset_current_kprobe();
> - return 1;
> + preempt_enable_no_resched();
> + break;
> #endif
> + case KPROBE_HIT_ACTIVE:
> + recursive_singlestep(p, regs, kcb);
> + break;
> + case KPROBE_HIT_SS:
> + if (*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
> + regs->flags &= ~TF_MASK;
> + regs->flags |= kcb->kprobe_saved_flags;
> + return 0;
> + } else {
> + recursive_singlestep(p, regs, kcb);
> + }
> + break;
> + default:
> + /* impossible cases */
> + WARN_ON(1);

WARN_ON() does not call panic(). Since the kernel doesn't stop,
we need to prepare singlestep after that.

How about this?
---
+ case KPROBE_HIT_ACTIVE:
+ break;
+ case KPROBE_HIT_SS:
+ if (*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
+ regs->flags &= ~TF_MASK;
+ regs->flags |= kcb->kprobe_saved_flags;
+ return 0;
+ }
+ break;
+ default:
+ /* impossible cases */
+ WARN_ON(1);
}
save_previous_kprobe(kcb);
set_current_kprobe(p, regs, kcb);
kprobes_inc_nmissed_count(p);
prepare_singlestep(p, regs);
kcb->kprobe_status = KPROBE_REENTER;
return 1;
}
---

Thank you,

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com, masami.hiramatsu.pt@hitachi.com



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